A short review on environmental distribution and toxicity of the environmentally persistent free radicals.

Environmentally Persistent Free Radicals (EPFRs) are usually generated by the electron transfer of a certain radical precursor on the surface of a carrier. They are characterized with high activity, wide migration range, and relatively long half-life period. In this review, we summarized the literature on EPFRs published since 2010, including their environmental occurrence and potential cytotoxicity and biotoxicity. The EPFRs in the atmosphere are the most abundant in the environment, mainly generated from the combustion of raw materials or biochar, and the C-center types (quinones, semiquinones radicals, etc.) may exist for a relatively long time. These EPFRs can transform into other substances (such as reactive oxygen species, ROS) under the influence of environmental factors, and partly enter soil and water by wet and dry deposition of particulate matter, which may promote the generation of EPFRs in those media. The wide distribution of EPFRs in the environment may lead to their exposure to biota including humans, resulting in cytotoxicity and biotoxicity. The EPFRs can influence the normal redox process of the biota, and generate a large number of free radicals like ROS. Exposure to EPFRs may change the expression of gene and activity of metabolic enzymes, and damage the cells, as well as some organs such as the lung, trachea, and heart. However, due to the difficulty in sample extraction, identification, and quantification of the specific EPFR individuals, the toxicity and exposure evaluation of biota are still limited which merits study in the future.

Young people exposure to antibiotics: Implication for health risk and the impact from eating habits of takeaway food.

Exposure to antibiotics, mainly from animal food ingestion, may have adverse effects on human health. Takeaway food is the preferred choice for the dietary of most Chinese young people nowadays, but the relationship between takeaway eating and antibiotic exposure is not yet adequately understood. In the present study, 297 young people were recruited to collect urine samples and questionnaires with an emphasis on their takeaway eating habits. The internal exposure to 16 antibiotics and three metabolites was measured in urine samples by high-performance liquid chromatography-tandem mass spectrometry, as well as a DNA oxidative damage marker, 8-hydroxydeoxyguanosine (8-OHdG). At least one kind of antibiotic was found in over 90 % of urine samples, with total concentrations from 0.667 to 3.02 × 104 ng/mL. High exposure levels of antibiotics were more likely to be found in individuals with a larger body mass index. The concentrations of six antibiotics were significantly different among people with different overall weekly eating frequencies, usually an upward trend. The estimated daily intakes of antibiotics were on the levels of 0.001-1.0 µg/kg/day, mainly contributed by clarithromycin, ciprofloxacin and oxytetracycline, indicating a potential health risk based on the microbiological effect. A significantly positive correlation was found between DNA oxidative damage and exposure for four categories of antibiotics, conformed by both Spearman correlation and multiple linear regression analysis. The levels of 8-OHdG were 355 %, 239 %, 234 %, and 334 % higher with elevated levels of phenicols, macrolides, tetracyclines and sulfonamides from quartiles 2 to 4. Our results suggest that high-frequency consumption of takeaways may exacerbate oxidative stress trends through human exposure to antibiotics.

Underlying Degradation of Phthalates via Microbials in Dust from Different Microenvironments.

Phthalate monoesters (me-PAEs) have been used as biomarkers for assessing human exposure to phthalate esters (PAEs) for a long time, and studies on the sources and distribution of me-PAEs in the environment are limited. In this study, dust samples from microenvironments were collected to measure the occurrence of PAEs and me-PAEs, as well as the bacterial diversity. The results indicated that me-PAEs coexisted with PAEs in different microenvironmental dust samples, with concentrations of nine PAEs and 16 me-PAEs ranging from 108 to 1450 µg/g (median range) and 6.00 to 21.6 µg/g, respectively. The concentrations of several low molecular weight me-PAEs (e.g., monomethyl phthalate and monoethyl phthalate) in dust were even significantly higher than those of their parents. The bacteria in the dust were mainly predominant with Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes (total abundance >90%). Bacteria from bus and air conditioning dust samples had the highest species richness and species diversity. Seven genes of suspected enzymes with the ability to degrade PAEs were selected, and the concentration of me-PAEs increased with increasing abundance of enzyme function. Our findings will provide useful information on the profiles of me-PAEs and their potential sources in indoor dusts, which will benefit the accurate estimation of human exposure.